This invention relates to a new and improved hermetically sealed container for semiconductor and other electronic devices and particularly to such a container designed and intended hermetically to seal semiconductor integrated circuit devices and the like.
The majority of semiconductor integrated circuit devices are housed in hermetically sealed packages commonly referred to as dual-in-line, flatpack, and hybrid packages. Several designs of such packages are now in use. Among these is one which consists of a ceramic base, a cover, a lead frame, and solder glass for sealing the frame between the base and the cover, known in the trade as the CERDIP package. Another package type consists of a lead frame sandwiched between layers of a glass-ceramic mixture. A cavity is left in one of the layers and the semiconductor device is sealed into the cavity with a metal lid and solder preform. Premolded and transfer-molded plastic packages are also used. One popular type of package is made from a single layer of ceramic having a screened, conductive lead frame pattern deposited on it, the terminal pins on the side of the package being brazed on to give a so-called "side braze" package. This type of package is also made with two layers of ceramic material with the screened conductive pattern sandwiched between the layers and ordinarily sealed with metal lids and metallic solder preforms. A number of packages comprising hybrids of those described above are also in use.
All of the above-described packages are relatively expensive and have certain disadvantages. The CERDIP package requires an excessively high temperature for hermetic sealing. The plastic transfer-molded method of packaging produces low yields because the semiconductor-to-lead-frame bonding wires are fragile and tend to be torn loose during the molding process. The plastic premolded package is relatively expensive and does not have hermetic sealing characteristics. The hybrid packages are subject to the disadvantages of their basic constituents.
It is an object of the present invention to provide a new and useful design for an hermetically sealed semiconductor package which is very low in cost, lends itself extremely well to automatic manufacture, requires relatively low tooling cost, and is a very rugged package having reliable hermetic sealing properties.